Which item below is not an example of how the general rule for dissolving works?

How many mmols of tris-hcl are there in 100 ml of a 100 mm tris-hcl buffer solution at ph 8.1? note that the 100 mm refers to the sum of tris and tris-hcl concentrations?

How many grams of oxygen gas are contained in a 15 l sample at 1.02 atm and 28°c? show your work.

How many moles is 14.5 cm^3 of platinum? the density of platinum is 21.45 g/cm^3.